Pool cues are commonly provided in two pieces that must be connected to assemble the pool cue for play. Typically, this connection is accomplished by means of a joint assembly comprising a pin portion and bushing portion, one located on each of the two pieces, to enable a standard type male-female coupling when the two portions are screwed together.
The most common joint pin and bushing on a pool cue, consists of a fully threaded pin that is screwed into a fully threaded (internal and external threads) brass insert. Aligning the two parts while trying to screw a two-piece pool cue together can be frustrating. If the two parts are not perfectly aligned, damage can be done when attempting to start the pin into the bushing, even to the extent of stripping the threads on one or both of the parts involved.
Joint assembly pins are commonly made of stainless steel and the bushings are made of brass. The stainless steel pins are made on a thread-rolling machine, but this method results in joint pins of variable tolerances and this makes it impossible to maintain a precision fit between the joint pins and bushings. The difficulty of maintaining precision fit is compounded when joint screws and brass inserts are made by different manufacturers. Among the problems involved is variation in the pitch on the threads between the joint pin and bushing. As a result, joint pins and bushings are not easily interchangeable between pool cues. Manufacturers of pool cues are thus currently unable to get joint pins and bushings that are reliably precision-fitting and interchangeable.
Lack of precision joint-assembly may result in several problems. Improper alignment of the portions of a joint can result in the stripping of the threads. Improper alignment also results in the two pieces of a pool cue being out of true and the pool cue being sub-optional for playing pool. It is also more difficult to accomplish assembly of the two pool cue pieces resulting in time wasted and frustration on the part of the user.
Some joint pin and bushing assemblies currently on the market attempt to accomplish a more precise alignment. However, they remain somewhat difficult to assemble and are relatively costly. They also have other flaws such as a bushing portion that allows glue to enter the interior of the bushing during assembly causing corruption of the joint assembly.
The present invention is directed to overcoming these limitations by providing an improved pool cue joint assembly that is self-aligning and that allows rapid and precise assembly of pool cue portions.
The joint assembly of the present invention is for use with pool cues comprising at least two pieces. The joint assembly is comprised of a bushing portion and a pin portion that are sized and structured to enable a typical male-female coupling when the joint is assembled. A precision alignment and fit of the bushing and pin is established by sizing and structuring the mating components so that a simultaneous close fit is achieved at two points: (1) where the nose of the pin meets an interior tapered region of the bushing located just prior to the internal threaded region of the bushing, and (2) where the smooth alignment portion of the pin first meets the smooth inner bore of the bushing. The bushing has a closed base to prevent glue from leaking into the bushing when the bushing is fastened to a portion of the pool cue.